Relation of Touch and Deep Sensation to Hand Reconstruction.

B UNNELL in tile United States and Hilgenfeldt in (3ermanv long ago stressed the fact that any grip with normal sensory function, even if weak, is preferred to a prosthesis. This fact is evident and easy to demonstrate by cases from one's own experience. A lack of sensibility only on the radial side of an index finger greatly impairs the facility to obtain a satisfactory result after a free tendon graft. It will constitute a minus factor as important as the presence of deep scarring to an index finger with normal sensibility. The linger without sensibility in the most important gripping area will not be used and, therefore, the graft will not get the amount of exercise necessary for success. The pinch will be performed with the middle finger, if this is normal. The same occurs in other attempted reconstructions. If sensibility is absent or poor, they will be bound to failure from a practical point of view. The patient will be unable to use the prehension otherwise obtainable. Paresthesia (hyperesthesia, hyperalgesia) is often a still more definitive obstacle to the use of fingers or parts of the lmnd. With the knowledge of such facts it becomes obvious that hand surgery of today cannot be satisfied with the old neurologic tests for sensibility nor with the discussion of this along the lines of the four modalities. This function is much more complicated and much less understood than usually believed. For its evaluation in our practical work it has been necessary to abandon entirely the tests with cottonwool and pins because they fail to differentiate between useful sensibility and paresthesia. Many examples of how easy it is to be mislead in this respect can be given. As is t)robably well known, the three tests of value so far available are the picking-up test, two point discrimination and the ninhydrin finger printing test. Each has its limitations and its advantages. Each also has its special technical details which must be carefully observed. Such details are described elsewhere. A great amount of equipment is not needed and any serious worker will soon learn to employ these tests. Without them no accurate work seems possible in this field. I would like to stress this point because 1 believe that especially in the important field of nerve grafting, work is going on for which they have not been used. Still, however, the tests available are very crude as compared with the complicated function they have to evaluate. When sensibility and especially tactile gnosis have been lost from the gripping part of the hand because of a nerve lesion, nerve suture is usually considered first. However, only in children can near normal sensibility be restored by nerve suture. This is true even in "ideal cases" in which only minimal scar tissue is present and there are no lesions except the one in the nerve. Ideal conditions necessitate that the suture be performed by a surgeon with special training and experience in the field. In adults, motor function of surprisingly great value often will return after such a suture. True tactile gnosis is obtained extremely rarely. Too often, only enough sensibility returns to permit response to pinprick and cottonwool tests which, as mentioned previously, does not mean function of practical value a t all. The result may be, instead, of a lower degree, sometimes enough for a coarse grip. Protective sensibility can usually be obtained (Onne 1962). No doubt the technic of nerve suture can be greatly improved. Recently my eel-